Infrared reflective materials are materials that reflect infrared rays included in sunlight or the like. The infrared reflective materials are used for relaxation of a heat island phenomenon, increase in air conditioning efficiency of buildings in summer, and the like because the infrared reflective materials can reduce the amount of infrared rays absorbed by a ground surface covered with asphalt, concrete, or the like, buildings, and the like.
As such an infrared reflective material, compounds containing chromium such as Cr2O3, Cu—Cr complex oxides, Fe—Cr complex oxides, Co—Fe—Cr complex oxides, and Cu—Cr—Mn complex oxides as black materials, for example, are known (see Patent Document 1). Compounds not containing chromium including complex oxides of an alkaline earth metal element and manganese such as Ca—Mn complex oxides, Ba—Mn complex oxides, and Ba—Mn complex oxides doped with 4% by weight of titanium dioxide (see Patent Document 2) and a complex oxide of a rare earth element and manganese such as Y—Mn complex oxide (see Patent Document 3) are also known. Compounds such as rod-like titanium oxide (see Patent Document 4) as white materials are also under development.